Security enclosures such as safes, strong boxes, and the like use combination locks which mount on an inside wall of the safe and have tumbler wheels with peripheral gate notches that must be aligned in order to be opened. The tumbler wheels are positioned by a driver fixed to a spindle which is rotated by the turning of a dial mounted on the outside of the safe. These tumbler wheels, along with other components of such locks, e.g., spacing washers, retaining nuts, etc., are supported on a bushing bolted to a mounting plate that attaches to the inner wall of the safe. Usually, these components are assembled at the time the lock is installed in the safe, and the installer must take special care to assure that the tumblers, while being readily movable, are not too loose and that their movement is smooth and consistent. However, with safes having heavy steel walls, it is not unusual to have slight misalignment problems between the spindle holes in the inner and outer walls. These alignment problems can cause the spindle to be canted in relation to the inner wall, i.e., not perpendicular to the surface of the inner wall; and this in turn makes it difficult to line up the cam driver or drive tumbler (fixed to the spindle) with the other lock components. This misalignment can cause stiffness in the movement of the lock components and/or can place uneven pressure on the tumbler wheels, moving them out of their parallel relationship and resulting in "skipping or dragging" during tumbler wheel movements.
For security reasons, it sometimes becomes desirable or necessary to change the combinations of such locks. This requires that changes be made to the tumbler wheels and/or to the drivers which position said tumbler wheels. Since such changes often require that the combination locks be dismantled and rebuilt with new or adjusted tumbler wheels, drivers, etc., such changes are usually relatively difficult, time consuming, and expensive.
We have invented a novel combination lock assembly that is relatively inexpensive, simple to assemble, and easily reset to any one of a plurality of combinations. Such resetting does not require the services of a professional lock expert but can be readily accomplished by the safe owner. Further, the tumbler wheels of our combination lock can be assembled in an independent assembly before being installed in a safe. This independent assembly can be tested, and the movement of the tumbler wheels can be adjusted for appropriate smoothness and consistency. This preinstallation adjustment of the assembly is not changed when the lock is installed. Further, in the event of spindle misalignment, as referred to above, the movement of our combination locks remains uniformly consistent because, even with uneven pressure on the drive tumbler wheel, the surfaces of all of the tumbler wheels remain parallel with each other so that they continue to interact smoothly and properly.
In one embodiment, this independent assembly of our combination lock incorporates a lock link and pin subassembly which can also be tested and adjusted prior to its installation in a smaller security enclosure such as strong box or hotel room safe.
Further, by virtue of this independent assembly feature of our invention, the security of the lock is increased. That is, since the tumbler wheel assembly is independent of the dial/spindle/driver mechanism, if the dial should be broken off and the spindle be punched out, the tumbler wheel assembly remains intact to prevent opening of the safe enclosure.